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Technetium ( 99 Tc)<br />

The soluble fraction of Tc contained in the spent fuels exists in the dissolution liquor as Tc(VII)<br />

(TcO4 - ). Its co-extraction with Zr(IV), then U(VI) and Pu(IV), by TBP is well known. So, for example,<br />

the separation of the Tc soluble fraction is achieved through a solvent special scrubbing step in the<br />

course of the implementation of the PUREX process at COGEMA La Hague reprocessing plants. If high<br />

Tc partitioning yield is required, the main problem concerns the recovery of the Tc fraction that is<br />

contained within the solid insoluble residues remaining after spent fuel dissolution. A special process is<br />

required for this Tc recovery, which actually does not exist.<br />

Caesium and strontium or caesium alone<br />

Many processes were developed worldwide in this field, including the use of:<br />

– Inorganic sorbents, like for the JAERI’s 4 group partitioning process.<br />

– Crown-ether extractants, like for the SREX and CSEX processes developed in the USA (ANL).<br />

– Cobalt dicarbollide extractants, as developed in Czech Republic, Russia and Western Europe.<br />

– Calix-crown extractants, as developed in France, Western Europe and in the USA.<br />

Most of these processes were successfully tested with radioactive effluents.<br />

2.3. Pyro processes for actinide partitioning [4]<br />

2.3.1 Selected media and possible separation techniques<br />

Selected media<br />

Most of the “pyro” processes developed so-far are based on the use of one or two of the following<br />

high temperature liquid phases:<br />

• Fused salts. The most popular fused salts studied are:<br />

– Molten chloride eutectic, such as LiCl+KCl.<br />

– Molten fluoride eutectic, such as LiF+CaF2.<br />

• Fused metal, such as Cd, Bi, Al, etc.<br />

Separation techniques<br />

To partition the actinides contained within the fused salt baths, three main techniques are studied<br />

and developed:<br />

• Actinide electrodeposition on solid (pyrographite or metal) or liquid metal cathodes.<br />

• Liquid-liquid extraction of actinide between fused salt bath and a metal bath containing a<br />

reductive metal solute (Li for example).<br />

• Actinide oxide precipitation from the fused salt under the proper control of the oxygen<br />

thermodynamic activity within the salt bath.<br />

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